JP7372395B2 - Glass plate suitable for image display devices - Google Patents

Description

The present invention relates to a glass plate, particularly a glass plate suitable for use in combination with an image display device.

A glass plate disposed on the image display side of an image display device, typified by a liquid crystal display device, is sometimes provided with an anti-glare function in order to suppress specular reflection of environmental light. The anti-glare function is achieved by minute deformations, specifically minute irregularities, formed on the surface of the glass plate. The anti-glare function is evaluated to be better as the value is smaller, using gloss as an index. On the other hand, light diffusion caused by minute irregularities is evaluated by haze. A small haze is desirable in order not to impair the clarity of the displayed image. Usually, minute irregularities are formed on the surface of a glass plate by a sandblasting method, an etching method, or a combination thereof.

As image display devices become more precise, a phenomenon called sparkle has become a problem. Sparkles are bright spots that occur depending on the relationship between minute irregularities on the main surface of anti-glare glass provided with an anti-glare function and the pixel size of an image display device. Sparkles are easily recognized as irregular light fluctuations, especially when the user's viewpoint moves relative to the image display device, but they can be observed even when the user's viewpoint is stationary.

Patent Document 1 describes a base surface with an arithmetic mean roughness Ra of 0.01 to 0.1 μm and an average spacing RSm of 1 to 20 μm, and a base surface with a diameter of 3 to 20 μm and a depth of 0.2 to 1 μm dispersed on this base surface. A glass plate is disclosed that has a main surface having a recess called a recess of .5 μm. This main surface is formed by applying an etching method after a sandblasting method. An example of Patent Document 1 discloses that a glass plate having the above-mentioned main surface was able to suppress sparkles.

Patent Document 2 discloses a glass plate having a main surface with an arithmetic mean roughness Ra of 0.02 to 0.4 μm and an average spacing RSm of 5 to 30 μm. The fine irregularities on the main surface are formed by an etching method using an etching solution with an adjusted composition, without performing pretreatment by sandblasting. The example of Patent Document 2 discloses that the glass plate having the above-mentioned minute irregularities was able to suppress sparkles.

Patent Document 3 discloses a glass plate in which the amount of change in gloss ΔGloss/ΔRMS with respect to the amount of change in surface roughness RMS is -800 or less. This glass plate is manufactured by an etching method involving pre-etching, in other words, by a two-step etching method. According to the Examples section of Patent Document 3, the smaller ΔGloss/ΔRMS is, the more sparkles are suppressed.

Japanese Patent Application Publication No. 2016-136232 Special table 2017-523111 publication International Publication No. 2014/112297

As sparkle is suppressed, it becomes difficult to control both gloss and haze to small values. For example, in Patent Document 2, Comparative Example 4 in which sparkle is not suppressed has a gloss of 75% and haze of 3.0%, whereas Example 8 in which sparkle is suppressed has a gloss of 75% and a haze of 13.6%. , the haze is about 10% higher when the gloss is the same. Also in Patent Document 3, the glosses of Examples 1 to 6 in which sparkle is suppressed are larger than the glosses in Examples 7 to 10 in which sparkle is not suppressed and the haze is in approximately the same range. From the above-mentioned first viewpoint, a glass plate having minute irregularities suitable for appropriately controlling gloss and haze while suppressing sparkle is desired.

A glass plate used in combination with an image display device is sometimes used as a touch panel. The surface of the touch panel is also required to provide a good operational feel to the user. From the above-mentioned second viewpoint, a glass plate having minute irregularities suitable for suppressing sparkle and providing a user with a good operational feeling is desired.

Conventional fine irregularities suitable for suppressing sparkles are basically irregular in size and position of the concave portions and convex portions, so it is not easy to accurately reproduce them during mass production. On the other hand, according to studies by the present inventors, unnatural reflected light, more specifically uneven reflected light, may be observed from minute irregularities with improved regularity in size and position. From the above third viewpoint, a glass plate with minute irregularities is desirable, which is suitable for suppressing sparkles, has high reproducibility during mass production, and is suitable for alleviating unevenness in reflected light generated from the glass plate itself.

Conventionally, the shapes of minute irregularities formed on the main surface of a glass plate by partially recessing the main surface by etching, etc. are circles, ellipses, and shapes with internal angles that are obtuse or smaller when viewed from the direction perpendicular to the main surface. It was limited to polygons that were angles or shapes that could be approximated to any of the shapes listed on the left. Furthermore, the shapes of the minute irregularities dispersed on the main surface are usually similar to each other. Therefore, the degree of freedom in designing the main surface is low, which is one reason why it is difficult to control other properties such as gloss and haze in a glass plate that suppresses sparkle. From the above fourth viewpoint, a glass plate that is suitable for suppressing sparkles and has a high degree of freedom in design is desirable.

An object of the present invention is to provide a glass plate that is suitable for suppressing sparkles and has excellent practicality from at least one of the above-mentioned viewpoints.

Considering the first aspect, the present invention provides, from its first aspect:
A main surface having a plurality of micro-deformed parts,
The plurality of minutely deformed portions are a plurality of recesses or a plurality of convex portions,
When the average value of the lengths of two mutually adjacent sides of the smallest right-angled quadrangle surrounding the micro-deformed part when observed from the direction perpendicular to the main surface is defined as the dimension of the micro-deformed part, the plurality of micro-deformed parts The average value of the dimensions of the deformed parts is 3.2 μm to 35.5 μm, and the number-based ratio of the micro-deformed parts A1 having the dimensions of 0.5 μm to 3.0 μm to the plurality of micro-deformed parts is 5. %, and/or the condition d1 that the coefficient of variation of the dimensions of the plurality of slightly deformed parts is 40% or less,
We provide glass plates.

Considering the second aspect, the present invention provides the following aspects:
A main surface having a plurality of micro-deformed parts,
The plurality of minutely deformed parts are a plurality of convex parts,
When the average value of the lengths of two mutually adjacent sides of the smallest right-angled quadrangle surrounding the micro-deformed part when observed from the direction perpendicular to the main surface is defined as the dimension of the micro-deformed part, the plurality of micro-deformed parts The average value of the dimensions of the deformed part is 3.2 μm to 35.5 μm,
We provide glass plates.

Considering the third aspect, the present invention first provides the following from its third aspect:
A main surface having a plurality of micro-deformed parts,
The plurality of minutely deformed portions are a plurality of recesses or a plurality of convex portions,
When the average value of the lengths of two mutually adjacent sides of the smallest right-angled quadrangle surrounding the micro-deformed part when observed from the direction perpendicular to the main surface is defined as the dimension of the micro-deformed part, the plurality of micro-deformed parts The average value of the dimensions of the deformed portion is 3.2 μm to 35.5 μm, and binarization processing to distinguish the plurality of minutely deformed portions from the surroundings by observing a 200 μm square area of the main surface from the direction. Either 3 to 30 bright spots are observed in the two-dimensional Fourier transformed image of the image subjected to A, or one bright spot is observed in the two-dimensional Fourier transformed image of the image subjected to the binarization process A. Two or more bright spots are observed in the two-dimensional Fourier transform image of the image that has been subjected to binarization processing B instead of digitization processing A,
We provide glass plates.
Here, the binarization process A is a binarization process that is executed by dividing the image into 256 x 256 pixels, and the binarization process B is a binarization process that is executed by dividing the image into 65536 x 65536 pixels. It is a process of conversion.

A two-dimensional Fourier transform image can be obtained from a processed image in which the image is divided vertically and horizontally into a predetermined number of pixels, and the pixels are binarized so that the minute deformation part and the surrounding area are distinguished. can. As described later, instead of the 200 μm square area of the main surface, binarization processing A or B is performed on the region of the main surface where there are 80 to 150 micro-deformed parts with dimensions of 0.5 μm or more. However, the number of bright spots may be counted based on a two-dimensional Fourier transformed image of the processed image. In this case, either 3 to 30 bright spots are observed in the two-dimensional Fourier transformed image of the image subjected to binarization processing A, or one bright spot is observed in the two-dimensional Fourier transformed image of the image subjected to binarization processing A. It is preferable that two or more bright spots are observed in a two-dimensional Fourier transformed image of an image that has been subjected to binarization processing B instead of binarization processing A. Note that the number of pixels during the binarization process is sometimes expressed as the number of "gradation" stages, and this specification follows this notation. In other words, for example, binarization processing at 256 x 256 gradations involves dividing the image vertically and horizontally into 256 equal sections, determining 256 x 256 sections, and performing binarization for each section (binarization). Process A). The number of gradations is set to an integer power of 2, and the bright spot detection sensitivity improves as the value increases.

Considering the fourth aspect, the present invention provides the following aspects:
A main surface having a plurality of micro-deformed parts,
The plurality of minutely deformed portions are a plurality of recesses or a plurality of convex portions,
When the average value of the lengths of two mutually adjacent sides of the smallest right-angled quadrangle surrounding the micro-deformed part when observed from the direction perpendicular to the main surface is defined as the dimension of the micro-deformed part, the plurality of micro-deformed parts The average value of the dimensions of the deformed parts is 3.2 μm or more, and when observed from the direction, the plurality of slightly deformed parts include i) a vertex of the right-angled quadrangular selected from the sides of the right-angled quadrilateral; a first minute deformation portion corresponding to a minute deformation portion having a straight line portion in contact with a part of the setback portion, or ii) a minute deformation portion having a polygon in which at least one interior angle is a dominant angle; a second minutely deformed portion having a shape different from that of the deformed portion;
We provide glass plates.

According to the present invention, it is possible to provide a glass plate that is suitable for suppressing sparkles and has high practicality. The glass plate provided by the first aspect of the present invention is suitable for appropriately controlling gloss and haze over a wide range while suppressing sparkle.

The glass plate provided by the second aspect of the present invention is suitable for providing a user with a good operational feeling while suppressing sparkle.

The glass plate provided by the third aspect of the present invention is suitable for suppressing sparkles, has high reproducibility in mass production, and is also suitable for alleviating unevenness in reflected light generated from the glass plate itself.

The glass plate provided by the fourth aspect of the present invention is suitable for suppressing sparkles and has excellent design freedom.

FIG. 2 is a plan view showing an enlarged part of the main surface of an example of the glass plate of the present invention. FIG. 2 is a cross-sectional view of FIG. 1 when the minute deformation portion is a convex portion. FIG. 2 is a cross-sectional view of FIG. 1 when the minute deformation portion is a recess. FIG. 3 is a plan view showing various shapes of minutely deformed parts. FIG. 7 is a plan view showing a rounded corner portion of a slightly deformed portion. It is a top view which expands and shows a part of main surface of an example of a conventional glass plate. FIG. 2 is an enlarged cross-sectional view of a part of the main surface of another example of a conventional glass plate. FIG. 2 is a diagram showing an image of a 50 μm square (50 μm×50 μm area) of the main surface of the glass plate of Example 1 observed with a scanning electron microscope (SEM). FIG. 3 is a diagram showing an image of a 50 μm square main surface of the glass plate of Example 2 observed by SEM. FIG. 3 is a diagram showing an image of a 50 μm square main surface of the glass plate of Example 3 observed by SEM. FIG. 3 is a diagram showing an image of a 50 μm square main surface of the glass plate of Example 4 observed by SEM. 5 is a diagram showing an image of a 50 μm square main surface of the glass plate of Example 5 observed by SEM. FIG. FIG. 6 is a diagram showing an image of a 50 μm square main surface of the glass plate of Example 6 observed by SEM. FIG. 7 is a diagram showing an image of a 50 μm square main surface of the glass plate of Example 7 observed by SEM. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 8 using an SEM, and a two-dimensional Fourier transform image (FT image) obtained from this image. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 9 using an SEM, and an FT image obtained from this image. FIG. 3 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 10 using an SEM, and an FT image obtained from this image. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 11 using an SEM, and an FT image obtained from this image. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 12 using an SEM, and an FT image obtained from this image. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 13 using an SEM, and an FT image obtained from this image. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 14 using an SEM, and an FT image obtained from this image. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 15 using an SEM, and an FT image obtained from this image. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 16 using an SEM, and an FT image obtained from this image. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of the glass plate of Example 17 using an SEM, and an FT image obtained from this image. FIG. 7 is a diagram showing an image of the main surface of the glass plate of Example 18 observed by SEM and an FT image obtained from this image. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of a glass plate obtained in the same manner as in Example 22 using an SEM. FIG. 7 is a diagram showing an image obtained by observing a 200 μm square main surface of a glass plate obtained in the same manner as in Example 27 using an SEM. FIG. 3 is a diagram showing the relationship between the gloss and haze of the glass plates of Examples 1 to 35 and Patent Documents 1 to 3.

Hereinafter, each embodiment of the present invention will be described, but the following description is not intended to limit the present invention to a specific embodiment. Repetitive explanations for each embodiment will basically be omitted. Descriptions of other embodiments are applicable to each embodiment unless clearly applicable to that embodiment.

[First embodiment]
First, one form of the glass plate provided from the first side will be described. In this one form, the glass plate has a main surface having a plurality of minutely deformed parts. The plurality of minutely deformed portions are a plurality of recesses or a plurality of convex portions. The plurality of minutely deformed portions have an average size within a predetermined range and satisfy a predetermined condition regarding size distribution. This condition is at least condition a1 and/or condition d1 described below.

As shown in FIG. 1, a plurality of minutely deformed portions 2 are formed on the main surface 1 of the glass plate 10. The minute deformation portion 2 is a minute region where the main surface 1 of the glass plate 10 is locally displaced in the thickness direction of the glass plate (also in the direction perpendicular to the plane of the paper in FIG. 1). The minute deformation portion 2 may be either a convex portion (FIG. 2A) or a concave portion (FIG. 2B). The cross-sectional shapes of the convex portions or concave portions shown in FIGS. 2A and 2B are examples, and the present invention is not limited thereto.

Although the minutely deformed portion 2 shown in FIG. 1 is circular when viewed from the direction perpendicular to the main surface 1, the shape of the minutely deformed portion is not limited to this. FIG. 3 shows minutely deformed portions 2A to 2K of various shapes. The shapes of the minutely deformed portions are, for example, circular 2A, elliptical 2B, polygons 2C to 2D and 2H to 2K, shapes 2E to 2F in which a plurality of these shapes are combined so that they touch each other or partially overlap, and the shapes on the left. This is a shape 2G in which one or more parts are removed from any of the shapes, or a shape that can be approximated to any of the shapes described on the left.

The shape of the minute deformation portion may be a polygon 2H to 2K in which at least one interior angle is a dominant angle, in other words, an angle greater than 180° and less than 360°. Examples of polygons having dominant interior angles include an L-shape 2H, a convex shape 2I, a crank shape 2J, and a pseudo-dumbbell shape 2K. When viewed from the direction perpendicular to the main surface 1, the slightly deformed portion 2H has one dominant angle 2p at its internal angle, and the slightly deformed portions 2I to 2K have two or more dominant angles 2p at their internal angles.

FIG. 3 is also only an example of the shape of the minutely deformed portion. Strictly speaking, the shape of the minutely deformed portion is determined based on the boundary between the minutely deformed portion 2 and the continuous portion 5 surrounding it, that is, the bottom in the case of a convex portion, and the opening in the case of a concave portion. This criterion is also applied to the area ratio and average shortest distance, which will be described later.

The corners of the actual minutely deformed portions may be slightly rounded. However, in order to categorize and describe shapes, in this specification, if the local deformation at a corner is less than 25% of the line segment that makes up the corner, this deformation will be ignored and the shape will be described. Describe. For example, although the slightly deformed portion 2L shown in FIG. 4 is precisely a square with rounded corners, it is treated as a square here.

The number of types of shapes of the minutely deformed portions may be two or more, three or more, or even four or more. Note that the number of types of shapes is determined by considering shapes that are similar to each other to be the same. The presence of multiple types of micro-deformation parts improves the degree of freedom in arranging the micro-deformation parts on the main surface. In particular, if the micro-deformed parts whose average dimensions are within a predetermined range are to be arranged so that the area ratio of the micro-deformed parts to the main surface is within a predetermined range and the micro-deformed parts maintain an average shortest distance of a predetermined length or more, multiple types of micro-deformed parts can be arranged. The use of a minutely deformed part having the shape improves the degree of freedom in the design of its arrangement, and facilitates the establishment of conditions that are difficult to coexist. The same applies to the case where the periodicity of the minutely deformed portions in the in-plane direction of the main surface should be reduced to a predetermined range.

Shapes A and B of the minutely deformed portions described below make a particularly large contribution to the improvement in the degree of freedom of design described above.
(Shape A) When viewed from the direction perpendicular to the main surface, a portion of the sides of the smallest right-angled quadrilateral surrounding the minutely deformed portion that does not include the vertices of the right-angled quadrilateral, in other words, a portion of the sides of the right-angled quadrilateral. A minutely deformed part (shape B) having a straight part that touches a region where a part of the right quadrilateral that does not include the vertices retreats into the inside of the right quadrilateral (hereinafter referred to as the "recessed part") when viewed from a direction perpendicular to the main surface. , a slightly deformed part that is a polygon in which at least one interior angle is a dominant angle.

The minutely deformed portions 2F and 2G correspond to shape A. These shapes have straight portions 2f and 2g that touch receded portions 3f and 3g where a part of the side of the virtual minimum right-angled quadrilateral 3 is recessed. Some of the sides of the right quadrilateral 3 that retreat to form the retreated portions 3f and 3g are set so as not to include the apex 3p of the right quadrilateral 3. Although the lengths of the straight portions 2f and 2g are not particularly limited, they are, for example, 1 μm or more, and more preferably 1.5 μm or more. Note that a shape in which circles partially overlap (see FIG. 5A), which is sometimes formed accidentally on the main surface of conventional anti-glare glass, does not have a straight line portion and does not correspond to shape A. The minutely deformed portions 2H to 2K correspond to shape B. The formation of shapes A and B has not been considered at all in conventional anti-glare glass. However, these shapes are useful when arranging the minutely deformed portions on the main surface without being too close to each other.

Preferably, the minutely deformed portion includes a first minutely deformed portion having a shape corresponding to shape A or shape B, and a second minutely deformed portion having a shape different from the first minutely deformed portion. The second minute deformation portion may have a shape corresponding to shape A or shape B, or may have another shape. The first minutely deformed portions may account for 10% or more, or even 20% or more, of the entire minutely deformed portions, or may account for 90% or less, or even 80% or less, of the entire minutely deformed portions. The second minute deformation portion can also be arranged on the main surface in a similar ratio.

The average shortest distance between the minutely deformed parts is preferably 4.5 μm or more, more preferably 7 μm or more, especially 15 μm or more, and may be 305 μm or less, further 150 μm or less, especially 80 μm or less, and even 50 μm or less in some cases. good. In this specification, the average shortest distance of minutely deformed portions is the square root of the number of minutely deformed portions that exist within the region of a right-angled quadrangle on the main surface of the glass plate, and is the length of one side of a square with the same area as the right-angled quadrangle. It shall be determined by excluding. However, whether a minutely deformed portion exists within the above region is determined based on the position of the geometric center of the minutely deformed portion. Further, the above-mentioned region is defined to include 30 or more, preferably 50 or more, and more preferably 80 to 100 minute deformations. Unless otherwise specified, the numerical values regarding the "dimensions" of the micro-deformed parts described below are also determined based on the micro-deformed parts in a certain area that is determined to have a similar number of micro-deformed parts.

The "dimensions" of the minutely deformed part are determined as follows. First, observation is made from a direction perpendicular to the principal surface 1, and a right-angled quadrilateral 3 with a minimum area surrounding the minutely deformed portion 2 is virtually set. Next, the lengths of the two adjacent sides 3a and 3b (see the minute deformations 2A and 2B in FIG. 3) of this virtual right-angled quadrilateral 3 are measured. Finally, calculate the average value of the lengths of the two sides 3a and 3b, and use it as the dimension. The dimension of the minutely deformed portion 2A, which is a circle, is the diameter of the circle.

The average value of the dimensions of the plurality of micro-deformed parts is 3.2 μm or more, in some cases 4 μm or more, even 5 μm or more, especially 5.5 μm or more, especially 6 μm or more, in some cases 7 μm or more, and even 9 μm or more. Preferably adjusted. When the average value becomes less than this and the number of fine micro-deformed parts increases, scattering of transmitted light due to Mie scattering becomes noticeable. In order to more reliably reduce the scattering of transmitted light and achieve a desired haze, it is desirable that the slightly deformed portion satisfy the following condition a1, more preferably condition a2, and even more preferably condition a3. , it is particularly desirable that condition a4 be satisfied, and it is especially desirable that condition a5 be satisfied.

(Condition a1) The ratio of the number of micro-deformed parts A1 having dimensions of 0.5 μm to 3.0 μm in the plurality of micro-deformed parts is less than 5%, preferably less than 3%.
(Condition a2) The ratio of the number of micro-deformed portions A2 having dimensions of 0.5 μm to 3.6 μm in the plurality of micro-deformed portions is less than 5%, preferably less than 3%.
(Condition a3) The ratio of the number of micro-deformed parts A3 having dimensions of 0.5 μm to 4.0 μm in the plurality of micro-deformed parts is less than 5%, preferably less than 3%.
(Condition a4) The ratio of the number of micro-deformed parts A4 having dimensions of 0.5 μm to 5.3 μm in the plurality of micro-deformed parts is less than 5%, preferably less than 3%.
(Condition a5) The ratio of the number of micro-deformed parts A5 having dimensions of 0.5 μm to 6.5 μm in the plurality of micro-deformed parts is less than 5%, preferably less than 3%.

In conventional anti-glare glass, no attention has been paid to minute irregularities with dimensions of about 0.5 μm to 3.0 μm. When a sandblasting/etching method or an etching method under conditions that develop surface irregularities is applied to the entire main surface of a glass plate, a considerable number of microscopic irregularities of this degree are generated, and Mie scattering of light in the visible range becomes noticeable. Cheap. FIG. 5A shows a typical example of the main surface of conventional anti-glare glass. The diameter distribution of the recesses, which are minute deformations present on the main surface 11, is extremely wide. The fact that a part of the recess is connected and integrated with an adjacent recess also further widens the diameter distribution of the recess.

FIG. 5B shows a cross section in a state where the main surface has further retreated from the state shown in FIG. 5A by etching or the like. In this state, the diameter of the recess increases and the continuous flat portion from the main surface 12 is lost. Even in the state shown in FIG. 5B, fine recesses remain and the diameter distribution of the recesses is still wide.

The upper limit of the average value of the dimensions of the minutely deformed portions may be determined as appropriate depending on the pixel density of the image display device used in combination with the glass plate, more specifically, the sub-pixel size of the image display device. , is preferably about half or less of the short side of the sub-pixel size. The upper limit of the average value of the dimensions of the minutely deformed portions is preferably set in the range of (d/1.9) μm, preferably (d/2) μm. Here, the sub-pixel size d is the short side of the sub-pixel.

In an image display device with a pixel density of 125 ppi, d is usually about 67.5 μm, so the upper limit of the average value of the dimensions of the minutely deformed portions 2 is 35.5 μm, preferably 33.8 μm. The above upper limit for an image display device with a pixel density of 264 ppi is 16.9 μm, preferably 16.0 μm. The above upper limit for an image display device with a pixel density of 326 ppi is 13.6 μm, preferably 13.0 μm.

Since the pixel density of an image display device that requires a glass plate having an anti-glare function is approximately 125 ppi or more, the upper limit of the average value of the dimensions of the minutely deformed portions is set to be 35.5 μm or less, and if necessary, It is best to set it to a small range. Specifically, when the short side of the sub-pixel size of the image display device used in combination is dμm, the average value of the dimensions of the minute deformation portion is 35.5 μm or less and (d/1.9) μm or less. It is recommended to set this.

For the reasons mentioned above, the average value of the dimensions of the minutely deformed portions is usually set to 3.2 μm to 35.5 μm. However, if there is a possibility that it will be applied to high-definition image display devices, the upper limit of the average value of the dimensions of the minutely deformed portions should be set to, for example, 16.9 μm or less, further 13.6 μm or less, and 12 μm if necessary. Hereinafter, the thickness may be particularly set to less than 10 μm.

As explained with reference to FIGS. 5A and 5B, in the conventional anti-glare glass, the diameter distribution of the recesses is extremely wide. Therefore, when the average value of the dimensions of the concave portions, which are minutely deformed portions, is adjusted to the above-mentioned range, the ratio of minute and minutely deformed portions having dimensions of about 0.5 μm to 3.0 μm increases. On the other hand, if etching is allowed to proceed in order to reduce the ratio of minutely deformed portions, the minutely deformed portions will become too large, making it impossible to suppress sparkles.

Depending on the shape of the minutely deformed portion, even if the dimension is slightly larger than the calculated value based on d, it may not cause sparkles. However, in order to suppress sparkles more reliably, it is desirable that the minutely deformed portion satisfy the following condition b and/or condition c.

(Condition b) The ratio based on the number of micro-deformed parts B having a size exceeding 35.5 μm among the plurality of micro-deformed parts is less than 15%, preferably less than 10%.
(Condition c) When the short side of the sub-pixel size of the image display device used in combination is dμm, the number of micro-deformation parts C that occupy more than (d/1.9) μm. The reference ratio is less than 15%, preferably less than 10%.

It is preferable that the dimensions of the minutely deformed portions are uniform with little variation. The coefficient of variation of dimensions measured for 50 arbitrarily selected, preferably 80 to 100 micro-deformed parts is, for example, 40% or less, 35% or less, 30% or less, 25% or less, 23% or less, and even 22%. or less, preferably 21% or less, more preferably 18% or less, in some cases 15% or less, 13% or less, 10% or less, further 5% or less, especially 3% or less. Conventionally, no attention has been paid to the coefficient of variation of the dimensions of minutely deformed parts. By focusing on the coefficient of variation, the following desirable condition d1 can be derived. Note that, as is well known, the coefficient of variation can be obtained by dividing the standard deviation by the average value.

(Condition d1) The coefficient of variation of the dimensions of the plurality of minutely deformed parts is 40% or less, and further, the above-mentioned value or less.

However, even if there is variation in the dimensions of the minutely deformed part, the above-mentioned coefficient of variation may be 3 to 40%, further 3 to 23%, especially 5 to 22%, and in some cases 5 to 21%. good. This degree of variation may contribute to alleviation of reflection unevenness. If emphasis is placed on alleviating reflection unevenness, the coefficient of variation may exceed 23%. For example, a glass plate in which the coefficient of variation of the dimensions of minutely deformed portions is in the range of 3 to 40%, and the average value of the dimensions is 13.6 μm or less, particularly 9 μm or more and 13.6 μm or less, can produce images with a pixel density of 326 ppi. In combination with a display device, it is suitable for suppressing sparkle and uneven reflection. In this case, the coefficient of variation is particularly preferably 12.3% or more, more preferably 12.5% or more, for example 12.3 to 35%. Further, in this case, if the number of bright spots in the two-dimensional Fourier transform image of the image subjected to the binarization processing A described above is 15 or less, reflection unevenness can be further suppressed.

In addition, when a plurality of micro-deformed parts having clearly different dimensions and which can be classified by size are intentionally formed, variations in the dimensions of the micro-deformed parts may be examined for each type. It can be said that "the dimensions are clearly different from each other" because, for example, a small deformed part on the main surface of a glass plate has a small deformed part α whose average value is μα and a minimum value minα, and a slightly deformed part α whose average value is This is a case where the relationship of μα>μβ and minα−maxβ>1 μm holds, including μβ and a minute deformation portion β whose maximum value is maxβ. The latter equation may be minα-maxβ>2 μm, or even minα-maxβ>3 μm. Furthermore, it can be said to be "classifiable" if there are substantially no minute deformations having dimensions between minα and maxβ. The term "substantially no micro-deformed parts having specific dimensions" means that the ratio of the corresponding micro-deformed parts, for example, the ratio of micro-deformed parts having dimensions between minα and maxβ is 3 of the total number of micro-deformed parts. %, especially less than 1%, especially less than 0.5%. In this example, the minutely deformed portion may further include a minutely deformed portion γ that has clearly different dimensions from each of the minutely deformed portions α and β and can be distinguished. If a plurality of types of minutely deformed portions that have clearly different dimensions and can be classified based on their dimensions are included, it is desirable that the following condition d2 be satisfied together with or in place of the condition d1.

(Condition d2)
If a plurality of micro-deformed parts with clearly different dimensions and differentiable dimensions are included, the coefficient of variation calculated for each dimension of each micro-deformed part (α, β, γ...) is They are respectively 23% or less, 22% or less, 21% or less, 15% or less, 10% or less, further 7% or less, preferably 5% or less. Note that each of the minutely deformed portions (α, β, γ, . . . ) is set to occupy 15% or more, 20% or more, or even 30% or more of the entire minutely deformed portions in terms of number.

It is preferable that the glass plate satisfies condition d1 and/or condition d2. The glass plate that satisfies condition d2 preferably satisfies condition a1 as a premise.

The plurality of minutely deformed portions 2 may be either convex portions or concave portions. However, a convex portion is preferable for the following reasons. First, for a glass plate used as a touch panel, convex portions can provide a surface with less resistance to fingers than concave portions. Therefore, the convex portion is advantageous when the user's operational feeling is important. Second, in the process of receding the glass surface by etching, etc., the dimensions of the concave portion may expand from the desired design value over time, whereas the dimensions of the convex portion may expand from the design value, so-called Dimension expansion due to over-etching can be easily prevented. For this reason, the convex portion is advantageous when sparkles should be prevented more reliably. As described below, each depression or protrusion is preferably surrounded by a substantially flat continuous section.

However, when the efficiency of etching processing, in other words, the small amount of glass to be etched is important, the recessed portion is advantageous.

The depth or height of the minutely deformed portion 2 is not particularly limited, but is, for example, 0.1 μm or more, preferably 0.2 μm or more, more preferably 0.3 μm or more, and, for example, 1 μm or less, preferably 0.8 μm or less. , more preferably 0.7 μm or less.

Returning to FIG. 1, the continuous portion 5 surrounding each of the minutely deformed portions 2 on the main surface 1 will be described. The continuous portion 5 is not separated by the minutely deformed portions 2, but extends between and around the minutely deformed portions 2. In other words, on the main surface 1, the minutely deformed portion 2 forms an island-shaped region surrounded by the continuous portion 5. Preferably, the continuous portion 5 is a substantially flat area. In this specification, a "substantially flat" region means that the surface roughness calculated using the formula for calculating the arithmetic mean roughness Ra based on the surface roughness curve in the region is 0.07 μm or less, preferably 0.07 μm or less. The range is 0.05 μm or less, more preferably 0.02 μm or less, particularly preferably 0.01 μm or less. Whether the surface is substantially flat can be evaluated by, for example, cross-sectional SEM observation. Note that, as is clear from FIG. 5B, there is no substantially flat area on the surface of the glass plate on which the unevenness has been developed by the conventional etching method. In conventional etching methods, in order to develop surface irregularities, etching is performed after sandblasting is performed in advance to generate fine recesses or while precipitates are locally generated. With these methods, it is practically impossible to control the starting point position and size distribution of the micro-deformed portions, so that when the unevenness develops, the flat area is lost from the surface of the main surface (FIG. 5B).

The substantially flat area may occupy 40% or more, 50% or more, or even 60% or more of the main surface of the glass plate. This region may occupy the remainder of the area occupied by the minutely deformed portion.

In FIG. 1, the same minute deformations 2 are regularly arranged on the main surface 1. This design is basically preferable in terms of stabilizing the characteristics of mass-produced products. A design in which micro-deformed portions of non-uniform size are irregularly arranged is likely to bond with each other and become integrated during processing such as etching, resulting in excessively large micro-deformed portions (see FIG. 5A). Furthermore, it is not easy to sufficiently suppress local differences in properties, especially for glass plates with large areas. Regular arrangement eliminates these disadvantages. However, unnatural rainbow-like unevenness of reflected light may be observed from the main surface where the arrangement of minutely deformed portions is highly regular. Although this unevenness is not as noticeable as sparkle, it is desirable to suppress it.

The unevenness of reflected light can be suppressed by relaxing the regularity of the arrangement of the minutely deformed parts. Specifically, a 200 μm square area of the main surface and/or a region of the main surface where 80 to 150 micro-deformed parts with dimensions of 0.5 μm or more exist are observed from a direction perpendicular to the main surface to determine the micro-deformation. 2 to 30, more preferably 3 to 30, preferably 5 to 25, more preferably 9 to 30 pieces are added to the two-dimensional Fourier transformed image of the image that has been subjected to the above-mentioned binarization process A to distinguish the deformed part from the surrounding area. The periodicity of the arrangement of the minutely deformed portions in the in-plane direction of the main surface is reduced to such an extent that 18 bright spots, particularly preferably 13 to 17 bright spots, and another more preferred example 5 to 15 bright spots are observed. It is preferable to let In conventional glass plates with an anti-glare function, there is no periodicity in the arrangement of minute deformations, or even if there is, the degree of periodicity is very low, so only one bright spot is observed in the above two-dimensional Fourier transform image. Only. On the other hand, an array with high periodicity as shown in FIG. 1 generates a large number of bright spots, approximately several hundred or more, in the two-dimensional Fourier transformed image.

Note that the "region of the main surface where 80 to 150 micro-deformed portions with dimensions of 0.5 μm or more exist" is preferably set as a right-angled quadrangular region on the main surface. In this case, the number of minutely deformed portions is counted including the minutely deformed portions that are partially present in the rectangular area.

If the regularity of the arrangement of the minutely deformed parts is relaxed, the number of bright spots described above may vary depending on the production lot or locally. This is thought to be because the position and size of the minutely deformed portions were affected by unavoidable slight variations in manufacturing conditions such as etching conditions. According to the inventor's study, such instability in the number of bright spots becomes noticeable when the average number of bright spots obtained under the manufacturing conditions is about 15 or less, and this effect causes the bright spots to become unstable. A glass plate may be obtained with the number of dots reduced to one. It has been confirmed that desired characteristics can be obtained from such a glass plate to the extent that it is substantially the same as a glass plate having two or more bright spots. This is considered to be due to the existence of regularity that cannot be confirmed by the binarization process A. In fact, when performing image binarization processing by applying a gradation higher than 256 x 256, for example 8192 x 8192, to a glass plate of a production lot in which the number of bright spots has been reduced to one, Two or more of the above-mentioned bright spots are observed. This is because the number of bright spots increases as the gradation becomes higher. Further, it is possible to obtain desired characteristics from a glass plate designed by further relaxing the regularity of the arrangement. However, depending on the degree of relaxation, the number of bright spots of 2 or more cannot be measured unless binarization is performed at a high gradation of about tens of thousands, such as in binarization process B, and the existence of regularity may not be confirmed. Taking the above into consideration, we assume that two or more bright spots can be confirmed by the gradation of 8192 x 8192, strictly speaking, by the binarization process B (65536 x 65536), and by the brightness by the binarization process A. This means that the minute deformation section may be designed so that the number of points is one. On the other hand, even if the conventional glass plates disclosed in Patent Documents 1 to 3 are measured with several thousand high gradations and even with the application of binarization processing B, the number of bright spots obtained is only one. Become.

The area ratio of the micro-deformed parts, more specifically, the ratio of the total area of the micro-deformed parts viewed from the direction perpendicular to the main surface to the area of the main surface is not particularly limited, but may be, for example, 1.5 to 60%, and is between 1.5 and 50%, particularly between 1.5 and 40%. The area ratio of the minutely deformed portion is preferably 2% or more, more preferably 5% or more, and in some cases 8% or more, preferably 45% or less, more preferably 40% or less, particularly preferably 30% or less, In some cases, it is 25% or less, further 23% or less, particularly 20% or less.

The glass plate having the minutely deformed portions described above is suitable for adjusting both gloss and haze to desired ranges while suppressing sparkle. Specifically, when gloss is expressed as X (%) and haze is expressed as Y (%), it is possible to satisfy the relationship of formula (I). Even if the micro-deformed portion is controlled finely enough to prevent sparkles even when used in combination with a 326 ppi image display device, specifically, for example, the average size of the micro-deformed portion is set to 3.2 μm to 13.6 μm. Even if it does, it is also possible to provide a glass plate that satisfies formula (I).

Y≦-1/6X+20 (I)

Studies by the present inventors have revealed that the practicality of the glass plate can be ensured even if the gloss is high to some extent, as long as the haze is sufficiently suppressed. The glass plate having the minutely deformed portions described above is also suitable for adjusting haze and gloss within such a range, and specifically can satisfy the relationship of formula (II).

Y≦-1/40X+8 (II)

In the glass plate having formula (II), the value of Y may be 6 or less, and further may be 5 or less. The values of X and Y may be limited to a range of 100≦X≦160, 0≦Y≦6, or further 100≦X≦150, 0≦Y≦5. Formula (II) may be Y≦−1/40X+7.5.

A glass plate having a minutely deformed portion provided by the present invention can satisfy at least one of the relationships of formulas (I) and (II).

Among the glass plates presented as comparative examples in Patent Documents 1 to 3, there are those whose haze and gloss are low enough to satisfy formula (I) and/or (II) (Patent Document 2 Comparison) Examples 1 to 5 and Patent Document 3 Experimental Example 8). However, conventionally, glass plates with such low haze and gloss have been unable to suppress sparkles, as reported in Patent Documents 1 to 3. This is because the entire micro-deformed portion is too large. It is difficult for such a glass plate to satisfy condition b, and it is also difficult to satisfy condition d1 due to large dimensional variations. On the other hand, if the dimensions of the entire micro-deformed portion are controlled so that sparkles are suppressed (each example of Patent Documents 1 to 3), the ratio of the micro-deformed portion increases and condition a1 is no longer satisfied, and especially haze becomes difficult to suppress. In the conventional etching methods disclosed in Patent Documents 1 to 3, it is difficult to uniform the dimensions of the minutely deformed portions to the extent that condition d1 is satisfied. Therefore, the examples of Patent Documents 1 to 3 do not satisfy the relationships of formulas (I) and (II).

In contrast to such conventional technical standards, according to the present embodiment, for example, in order to suppress sparkles, the pixel density is equal to or less than a value calculated from 326 ppi, specifically, 13.6 μm or less, further 12 μm or less, depending on the case. Even if the average value of the dimensions of the minutely deformed portions is limited to less than 10 μm, it is possible to provide a glass plate that satisfies the relationship of formula (I) and/or (II). In other words, the present invention can also provide the following glass plates from the above-mentioned aspects.

A main surface having a plurality of micro-deformed parts,
The plurality of minutely deformed portions are a plurality of recesses or a plurality of convex portions,
When the average value of two mutually adjacent sides of the smallest right-angled quadrangle surrounding the micro-deformed part when observed from the direction perpendicular to the main surface is defined as the dimension of the micro-deformed part, the size of the plurality of micro-deformed parts is The average value of the dimensions is 3.2 μm to 13.6 μm, and at least one of formulas (I) and (II) is satisfied when gloss is expressed as X (%) and haze is expressed as Y (%). ,
glass plate.

This glass plate may further satisfy condition b and/or condition c, may satisfy condition d1 and/or condition d2, and may have other characteristics described in the first embodiment. Good too. In this specification, gloss is measured according to "Method 3 (60 degree specular gloss)" of "Specular gloss measurement method" of Japanese Industrial Standard (JIS) Z8741-1997, and haze is measured according to JIS K7136:2000. Ru.

[Second embodiment]
Next, one form of the glass plate provided from the above-mentioned second side will be described. In this one form, the glass plate has a main surface having a plurality of minutely deformed parts. The plurality of minutely deformed portions are a plurality of convex portions. Preferably, each of the plurality of micro-deformations is surrounded by a substantially flat continuous section. The plurality of minutely deformed portions have an average size within a predetermined range.

Also in this embodiment, the average size of the minutely deformed portions is set within the range of 3.2 μm to 35.5 μm. The shapes, dimensions, mutual distances, and preferable ranges and conditions of the area ratios of the minutely deformed portions are as described in the first embodiment. Also in this embodiment, it is preferable to reduce the periodicity of the arrangement of the minutely deformed portions to such an extent that the number of bright spots described in the first embodiment can be observed in the two-dimensional Fourier transformed image. According to this embodiment as well, it is possible to provide a glass plate that satisfies formula (I) and/or (II), and it is also possible to provide other features described in the first embodiment.

However, in this embodiment, the minute deformation portion formed on the main surface is a convex portion. The preferred range of the height of the convex portion is as described in the first embodiment. Since the minutely deformed portion is a convex portion, it is possible to provide a user who uses a glass plate as a touch panel with a superior operational feeling. The difference in operational feel from a glass plate in which the minutely deformed portions are concave portions becomes more noticeable in an environment with low relative humidity. In addition, since the dimensions of the convex portion can be easily controlled to below a predetermined limit when manufacturing the minutely deformed portion, sparkles can be more reliably prevented by the convex portion. Furthermore, when the continuous portion surrounding the convex portion is substantially flat, the main surface of the glass plate according to this embodiment makes it relatively easy to remove dust adhering from the atmosphere and sebum transferred from the user's fingers. .

[Third embodiment]
Furthermore, one form of the glass plate provided from the above-mentioned third aspect will be described. In this one form, the glass plate has a main surface having a plurality of minutely deformed parts. The plurality of minutely deformed portions are a plurality of recesses or a plurality of convex portions. The plurality of minutely deformed portions have an average size within a predetermined range. A predetermined two-dimensional Fourier transformed image obtained from the main surface has a number of bright spots within a predetermined range. The number of objects in the predetermined range can be determined based on the case where the binarization process is performed at a gradation of 256 x 256 (binarization process A) and, if necessary, further 65536 x 65536 (binarization process B). .

Also in this embodiment, the average size of the minutely deformed portions is set within the range of 3.2 μm to 35.5 μm. The shapes, dimensions, mutual distances, and preferable ranges and conditions of the area ratios of the minutely deformed portions are as described in the first embodiment. Also in this embodiment, the minute deformation portion is preferably a convex portion, and its preferable height is as described in the first embodiment. Also according to this embodiment, it is possible to provide a glass plate that satisfies formula (I) and/or (II).

However, in this embodiment, the arrangement of minute deformation parts is not a highly periodic arrangement as shown in FIG. 1, but 3 to 30, preferably 5 to 25, The periodicity is such that a number of bright spots can be observed, more preferably 9 to 18, particularly preferably 13 to 17, and another preferred example 5 to 15. Periodicity relaxed to this extent is suitable for both ensuring reproducibility during mass production and alleviating unevenness in reflected light generated from the light itself. As described above, when the periodicity is relaxed, the number of bright spots may be reduced to only one depending on the manufacturing lot. However, in this case as well, if binarization processing B is performed with a gradation higher than 256 x 256, for example several thousand gradations, or even 65536 x 65536, two or more bright spots will be observed, so the degree of Although it is low, periodicity can be confirmed.

As mentioned above, a two-dimensional Fourier transform image is a 200 μm square area of the main surface of a glass plate, or a region of the main surface where 80 to 150 micro-deformed parts with dimensions of 0.5 μm or more exist, perpendicular to the main surface. It can be obtained from an image that is observed from a different direction and subjected to binarization processing to distinguish the minutely deformed portion from surrounding areas. Setting a region with each side of 200 μm can be easily performed. On the other hand, setting the area based on the number of regions is more suitable for correctly evaluating the periodicity of the minutely deformed portions on the main surface where the distribution density of the minutely deformed portions is small.

In this embodiment, instead of the condition that the two-dimensional Fourier transformed image of the glass plate has a predetermined number of bright spots, the condition that the coefficient of variation of the dimensions of the minutely deformed portion is 3 to 40%, or even 3 to 23% is used. There may be a condition that there is. In this case, the preferred range of the coefficient of variation is 5 to 22%, more preferably 8 to 21%, particularly 12.5 to 21%.

In this embodiment, instead of the condition that the two-dimensional Fourier transformed image has a predetermined number of bright spots, the glass plate has the condition that the coefficient of variation of the dimension of the minute deformation part is 3% or more, and the condition a1. , that is, the ratio of minute deformed portions may be small. In this case, the preferred range of the coefficient of variation is 5% or more, further 8% or more, particularly 12.5% or more.

[Fourth embodiment]
Next, one form of the glass plate provided from the above-mentioned fourth aspect will be described. In this one form, the glass plate has a main surface having a plurality of minutely deformed parts. The plurality of minutely deformed portions are a plurality of recesses or a plurality of convex portions. The plurality of minutely deformed portions have an average size within a predetermined range. The plurality of small deformation parts include a first small deformation part having a predetermined shape, and a second deformation part having a shape different from the first small deformation part.

In this embodiment, the average dimension of the minutely deformed portion is set to be 3.2 μm or more, for example, in the range of 3.2 μm to 50 μm, preferably in the range of 3.2 μm to 35.5 μm. Even if the first minutely deformed portion has a large apparent size, it is difficult to generate sparkles. The shapes, dimensions, mutual distances, and preferable ranges and conditions of the area ratios of the minutely deformed portions are as described in the first embodiment. Also in this embodiment, the minute deformation portion is preferably a convex portion, and its preferable height is as described in the first embodiment. Also in this embodiment, it is preferable to reduce the periodicity of the arrangement of the minutely deformed portions to such an extent that the number of bright spots described in the first embodiment can be observed in the two-dimensional Fourier transformed image. Also according to this embodiment, it is possible to provide a glass plate that satisfies formula (I) and/or (II).

However, in this embodiment, the minutely deformed portion includes a first minutely deformed portion corresponding to the above-described shape A or shape B, and a second minutely deformed portion having a shape different from the first minutely deformed portion. The second minute deformation portion may or may not correspond to shape A or shape B. The preferable abundance ratio of the first slightly deformed portion and the second slightly deformed portion is as described in the first embodiment. The formation of the first minutely deformed portion was not previously intended, and as is clear from its distinctive shape, by combining it with the second minutely deformed portion, it is possible to create a minutely deformed portion on the main surface. Improve flexibility in layout design. The characteristic shape of the minutely deformed portion makes it easy to adjust the area ratio and regularity of the minutely deformed portion.

[Embodiment as an image display device]
Finally, an embodiment as an image display device will be described. As one form of the present invention, the present invention includes an image display device whose sub-pixel size has a short side of dμm, and a glass plate disposed on the image display side of the image display device, the glass plate having the above-mentioned first to An image display device including a glass plate, which is the glass plate described in at least one of the fourth embodiments, is provided. However, the average size of the minutely deformed portions of the glass plate is preferably set in a range of 3.2 μm or more (d/1.9) μm or less, particularly 4 μm or more and (d/2) μm or less.

[Glass plate]
There are no particular restrictions on the composition of the glass plate. The glass plate may have various compositions such as soda lime glass, aluminosilicate glass, and alkali-free glass. The thickness of the glass plate is not particularly limited, but is, for example, in the range of 0.1 mm to 4.0 mm, particularly in the range of 0.5 mm to 3.0 mm.

[Processing of glass plate]
(strengthening treatment)
The glass plate may be subjected to physical strengthening treatment or chemical strengthening treatment, if necessary. Since these processes can be performed using conventional methods, their explanation will be omitted here.

(thin film formation)
If necessary, a thin film may be formed on the surface of the glass plate in order to add various functions. The thin film may be formed on the main surface 1 on which the minutely deformed portion 2 is arranged, or may be formed on the opposite main surface. Examples of the thin film include anti-reflection films and anti-fingerprint films. Since these thin films can also be formed by conventional methods, their explanation will be omitted here. The thin film is typically formed by a vapor deposition method such as a vacuum evaporation method, a sputtering method, or a chemical vapor deposition method, or a wet film deposition method such as a sol-gel method.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the following Examples are not disclosed with the intention of limiting the present invention.

[Preparation of glass plate]
Microscopic irregularities, which are microdeformed parts, were formed on the main surface of the glass plate in the following manner. The glass plate used was aluminosilicate glass with a thickness of 1.1 mm. Various fine irregularities were formed on one main surface of this glass plate by photolithography. Hydrofluoric acid (hydrogen fluoride aqueous solution) with a concentration of 1.5 wt % was used as an etching solution for etching performed subsequent to the development and cleaning of the photomask. Etching was carried out so that the depth of the recesses or the height of the protrusions formed was approximately 0.3 to 0.6 μm.

Note that the glass plate of Example 18 was produced not by photolithography but by sandblasting and etching with hydrofluoric acid.

[Evaluation of glass plate]
Evaluation of the glass plate was carried out as follows.
(Dimensions and area ratio of minute deformation part)
Using SEM, the main surface of the micro-deformed portion was observed over a width of 126×95 μm, and the area ratio and dimensions of the micro-deformed portion were measured. The dimensions of 84 minutely deformed parts were measured.

(Gross and haze)
Gloss was measured based on "Method 3 (60 degree specular gloss)" of "Method for measuring specular gloss" of JIS Z8741-1997. Haze was measured based on JIS K7136:2000.

(FT bright spot number)
Image processing software "Imagej 1.50i" was used to measure the number of bright spots in the two-dimensional Fourier transformed image. This software is in the public domain and includes Fourier analysis capabilities. Specifically, a threshold value was set so that a minutely deformed part could be distinguished from its surroundings in an image obtained by SEM observation, a Fourier transform image was created, and the number of volatile points appearing in the image was counted. The analysis using the above software was basically carried out at 256 x 256 gradations (binarization processing A), and in the case described later, it was carried out at 65536 x 65536 gradations (binarization processing B).

(Sparkle suppression effect)
The main surface of the 125ppi and 326ppi displays with minute irregularities formed on the surface faces the outside of the display, with a gradation display (R, G, B) of (0, 255, 0) in which only the green sub-pixel emits light. We placed a glass plate on top of the display and evaluated the flickering of the image while keeping the display stationary. The results were evaluated based on the following.
×: Flickering on the screen can be observed.
△: Slight flickering of the screen can be observed.
○: Flickering on the screen cannot be confirmed.

(Uneven reflection)
A 20 W fluorescent lamp was installed above the examination table with a black surface, and a glass plate was held approximately 30 cm below the fluorescent lamp. In this state, the surface reflection of the main surface of the glass plate was observed from a position approximately 30 cm away from the glass plate. The results were evaluated based on the following.
×: Rainbow interference colors can be confirmed.
○: Slight interference color can be observed.
◎: Interference color cannot be confirmed.

The results are shown in Tables 1 and 2. Further, the results of observing the main surfaces of the glass plates obtained from Examples 1 to 18 using SEM are shown in FIGS. 6 to 23. Each SEM image observes a 50 μm square area (Figures 6 to 12; Examples 1 to 7), a 200 μm square area (Figures 13 to 22; Examples 8 to 17), and a 100 μm square area (Figure 23; Example 18). This is what I did. 13 to 23 also show two-dimensional Fourier transformed images obtained from the obtained SEM images. The bright spot in this converted image is located at a position surrounded by a circle. In Examples 1 to 7, at least more than 100 bright spots were confirmed by measuring a 50 μm square area, so measurements targeting a 200 μm square area where the number of bright spots would further increase were omitted. Regarding Example 18, a two-dimensional Fourier transform image of a 200 μm square area was also observed, but the number of bright spots was only one, as in FIG. 23. Although not shown, in Examples 19 to 35, minute deformations were also formed on the main surface of the glass plate.

In addition, when a two-dimensional Fourier transform image was created in the same manner as described above for the SEM images of FIGS. 1 and 2 of Patent Document 2, the number of bright spots was 1, as in Example 18. In any of the conventional anti-glare glasses, it was not possible to confirm the periodicity of the minute deformation portions in the in-plane direction of the main surface.

If a glass plate designed to have a relatively small number of bright spots, specifically 15 or less, or even 10 or less, is manufactured repeatedly, the number of bright spots will be lower than the values shown in Tables 1 and 2 depending on the production lot. In some cases, the number of bright spots is also small, and some samples have been confirmed to have one bright spot. The results of observation of such a sample using SEM are shown in FIGS. 24 and 25. 24 and 25 are results obtained from samples obtained by applying the same manufacturing conditions as Examples 22 and 27, respectively. However, regarding each item in Table 2 except for the number of bright spots, these samples gave almost the same good results as Examples 22 and 27, respectively. Furthermore, when we analyzed the samples shown in Figures 24 and 25 using software at higher gradations, specifically 8192 x 8192 or higher gradations, and counted the number of FT bright spots, we found that each A score of 2 or more appeared. In Examples 32 to 35, the number of FT bright spots was 1 according to binarization processing A, but the software analysis was performed at a higher gradation, specifically, at a gradation of 65536 x 65536 (binarization processing B). When carried out, the number of FT bright spots was 2 or more. On the other hand, even when the sample of Example 18 was analyzed at a similar high gradation level, the number of bright spots remained 1.

Furthermore, a tactile test was conducted on the main surface of the glass plate for Examples 13 and 14 in which the area ratio of the micro-deformed portions was approximately the same but the shape (concave or convex) of the micro-deformed portions was different. This test was conducted by rubbing the main surface with a dry fingertip about 5 times. Example 14, in which the minutely deformed portion was a convex portion, had better tactile sensation than Example 13. Similar tactile tests were conducted on other glass plates, and it was found that when the area ratios were in the same range, glass plates with convex micro-deformations had a better tactile feel than glass plates with concave micro-deformations. It was confirmed that

In addition, the surface roughness curves of the continuous parts of Examples 1 to 17 were measured using a cross-sectional SEM, and the average roughness was calculated from the curves using the same formula as the arithmetic mean roughness Ra for the parts corresponding to the connecting parts. , the values were all 0.008 μm or less. Furthermore, when the average roughness was similarly calculated for the tops of the convex portions or the bottoms of the concave portions, which were the minutely deformed portions of Examples 1 to 17, the values were all 0.008 μm or less. Similar measurements were carried out for Examples 19 to 35, and the average roughness was similarly kept low.

FIG. 26 shows the relationship between gloss and haze for Examples 1 to 16 and 19 to 35. The solid diagonal line shown in FIG. 26 is expressed as Y=-1/6X+20 when gloss is expressed as X (%) and haze is expressed as Y (%). The characteristics of the glass plates of Examples 1 to 16 in Table 1 are shown below this straight line in FIG. 26, more specifically between the above diagonal line and the diagonal line not shown in FIG. 26 represented by Y=-1/6X+15. is plotted. In particular, the glass plates of Examples 1 to 6 have an average size of 3.2 μm to 13.6 μm, and when used in combination with an image display device with a pixel density of 326 ppi, sparkle can be suppressed, while gloss and haze can be suppressed compared to conventional glass plates. It is also a well-balanced reduction.

In Examples 19 to 35, the haze is sufficiently suppressed, but the gloss is slightly high, and except for Examples 22, 25, and 27, the relationship Y≦−1/6X+20 is not satisfied. However, it was confirmed that these samples also had properties that caused no problems in practical use. In particular, in the glass plates of Examples 19 to 35, when combined with an image display device with a pixel density of 326 ppi, sparkle was suppressed, haze was sufficiently reduced, and reflection unevenness was well suppressed. The dashed diagonal line shown in FIG. 26 is indicated by Y=-1/40X+8. The properties of the glass plates of Examples 19-35 are plotted below this straight line in FIG.

PD1 to PD3 plotted in FIG. 26 indicate the characteristics of glass plates disclosed as examples in which sparkle can be suppressed in Patent Documents 1 to 3, respectively. Although the glass plates of the examples of Patent Documents 1 to 3 suppress sparkle when combined with an image display device with a pixel density of 326 ppi, they have not succeeded in suppressing both gloss and haze. As shown in these documents as comparative examples, the techniques of Patent Documents 1 to 3 cannot appropriately set gloss and haze unless generation of sparkles is allowed. It is thought that the glass plates of the Examples of Patent Documents 1 to 3 had slightly inferior characteristics because they had a high proportion of minutely deformed portions with dimensions of about 3 μm or less. With the conventional techniques disclosed in these patent documents, it is difficult to form minutely deformed portions with appropriate dimensions while suppressing dimensional variations.

In conventional anti-glare glasses such as those shown in Patent Documents 1 to 3, the shape and arrangement of minute irregularities formed on the main surface thereof are not controlled. Therefore, a slight difference in manufacturing conditions may cause a large change in characteristics. For example, for the glass plate marked * closest to the solid diagonal line in Figure 26 (66% gloss, 9.6% haze), both the gloss and haze significantly increase by shortening the etching time by 5 seconds (75% gloss). , haze 13.6%; see Examples 8 and 9 of Patent Document 2).

Referring to Examples 1 to 4 and 6 to 7 in Table 1, the coefficient of variation (standard deviation/average value) of dimensions calculated from the examples in which the standard deviation of dimensions was measured is approximately 2.8 to 2.9%. It became small enough. Furthermore, in Example 5, there are two types of micro-deformed parts α and β that have clearly different dimensions and can be distinguished (the minimum dimension of the micro-deformed part α is 2 μm or more larger than the maximum dimension of the micro-deformed part β). The dimensional variation coefficients calculated for each minutely deformed portion were both about 2.8 to 2.9%.

Even in Examples 8 and 9, where the minutely deformed portions appear to be arranged randomly, it was confirmed that there was periodicity in the arrangement when a region containing a considerable number of the minutely deformed portions was judged as the target. In both Examples 8 and 9, there are 130 to 140 minute deformations in a 200 μm square, and the corresponding number of FT bright spots is 5. On the other hand, in both Examples 8 and 9, the number of FT bright spots obtained from a 100 μm square area including a minutely deformed portion of about 1/4 of this was only one, similar to the conventional random minutely deformed portion. In determining the periodicity of the minutely deformed portions based on the number of FT bright spots, it is desirable to set the region to include 80 to 150 minutely deformed portions in order to ensure accuracy. Setting the area based on such a number is considered to be particularly effective for the main surface where the average shortest distance of the minutely deformed portions is longer than in the illustrated example and the distribution density thereof is smaller than in the illustrated example.

Referring to Examples 8 to 10, 12 to 13, and 15 in Table 1, and Examples 19 to 35 in Table 2, the coefficient of variation is in the range of 3 to 35%, and the variation is somewhat large. Even if variations in the dimensions of the minutely deformed portions were observed to this extent, sufficient effects including the sparkle suppressing effect were obtained. Further, a coefficient of variation as large as this was effective in suppressing reflection unevenness. In Examples 5, 11, 14, and 16, there are minutely deformed portions that have clearly different dimensions and can be distinguished, and when looking at each type of minutely deformed portion, the variation in the dimensions is small. Similar to Example 5, in Examples 11, 14, and 16, the coefficient of variation of the dimensions of the minutely deformed portions for each classifiable type was 23% or less within the confirmed range. Furthermore, in Example 32, the variation in dimensions of the minutely deformed portions is suppressed to a very small level. Even in such a glass plate, if the regularity of the arrangement of the minutely deformed parts is relaxed (the number of FT bright spots by binarization processing A: 1), the reflection unevenness can be improved to some extent.

On the other hand, the average size of the minutely deformed portions in Example 17 exceeded 40 μm, and no sparkle suppressing effect was obtained. In Example 18, the average size of the minutely deformed portions was about 2 μm. Unlike Examples 1 to 17 and 19 to 35, Example 18 had many minute deformations with dimensions of 0.5 to 3.0 μm, and the transmitted light was extremely cloudy. In addition, in Example 18, each micro-deformation part is not surrounded by a substantially flat area, and such a region exists, even in that the micro-deformation part is formed on almost the entire main surface. This was different from other examples in which the area ratio of the minutely deformed portion was less than half (see FIGS. 6 to 25).

In Table 1, in Examples 1 to 16, the ratio based on the number of minutely deformed portions A2 with dimensions of 0.5 μm to 3.6 μm was less than 3%. In Examples 7 to 16, the ratio based on the number of minutely deformed portions A3 having dimensions of 0.5 μm to 4.0 μm was less than 3%. In Examples 10 to 16, the ratio based on the number of minutely deformed portions A4 having dimensions of 0.5 μm to 5.3 μm was less than 3%. In Examples 10 to 11 and 14 to 16, the ratio based on the number of minutely deformed portions A5 having dimensions of 0.5 μm to 6.5 μm was less than 3%. Furthermore, in Table 2, in Examples 19 to 35, the ratio based on the number of minutely deformed portions A2 having dimensions of 0.5 μm to 3.6 μm was less than 3%. In Examples 23 to 35, the ratio based on the number of minutely deformed portions A3 having dimensions of 0.5 μm to 4.0 μm was less than 3%. In Examples 28 to 35, the ratio based on the number of minutely deformed portions A4 having dimensions of 0.5 μm to 5.3 μm was less than 3%. In Examples 30 to 35, the number-based ratio of minutely deformed portions A5 having dimensions of 0.5 μm to 6.5 μm was less than 3%. Further, in Examples 1 to 10, 12 to 13, 15 to 16, and 18 to 35, the ratio based on the number of minutely deformed portions B having a dimension of more than 35.5 μm was less than 15%.

Note that according to photolithography-etching as described in this example, glass exhibiting good performance can be manufactured with good reproducibility. This manufacturing method is also suitable for significantly reducing product-to-product variation and defect rate.

The glass plate according to the present invention is particularly useful as a glass having an anti-glare function to be placed on the image display side of an image display device.

Claims (12)

A main surface having a plurality of micro-deformed parts,
The plurality of minute deformation parts are a plurality of recesses ,
When the average value of the lengths of two mutually adjacent sides of the smallest right-angled quadrangle surrounding the micro-deformed part when observed from the direction perpendicular to the main surface is defined as the dimension of the micro-deformed part, the plurality of micro-deformed parts The average value of the dimensions of the deformed parts is 3.2 μm to 35.5 μm, and the number-based ratio of the micro-deformed parts A1 having the dimensions of 0.5 μm to 3.0 μm to the plurality of micro-deformed parts is 5. %, and/or the condition d1 that the coefficient of variation of the dimensions of the plurality of slightly deformed parts is 40% or less ,
3 to 30 bright spots are observed in a two-dimensional Fourier transformed image of an image obtained by observing a 200 μm square area of the principal surface from the direction and performing binarization processing A to distinguish the plurality of minute deformations from the surroundings. or one bright spot in the two-dimensional Fourier transform image of the image that has undergone the binarization process A, or the two-dimensional Fourier transform of the image that has undergone the binarization process B instead of the binarization process A. A glass plate on which two or more bright spots are observed in each image .
Here, the binarization process A is a binarization process that is executed by dividing the image into 256 x 256 pixels, and the binarization process B is a binarization process that is executed by dividing the image into 65536 x 65536 pixels. It is a process of conversion. The glass plate according to claim 1, wherein each of the plurality of minutely deformed portions is surrounded by a substantially flat continuous portion on the main surface. The glass plate according to claim 1, wherein the ratio of the total area of the plurality of minutely deformed parts to the area of the main surface is 1.5 to 60%. The glass plate according to claim 1, wherein a coefficient of variation of the dimensions of the plurality of minutely deformed portions is 23% or less. The glass plate according to claim 1, wherein a coefficient of variation of the dimensions of the plurality of minutely deformed portions exceeds 23%. The glass plate according to claim 1, which satisfies a condition a2 that a number-based ratio of the micro-deformed portions A2 having the dimensions of 0.5 μm to 3.6 μm in the plurality of micro-deformed portions is less than 5%. 7. The glass plate according to claim 6, which satisfies condition a3 that a number-based ratio of the micro-deformed portions A3 having the dimensions of 0.5 μm to 4.0 μm in the plurality of micro-deformed portions is less than 5%. The glass plate according to claim 1, wherein the average value of the dimensions of the plurality of minutely deformed portions is 3.2 μm or more and 13.6 μm or less. The glass plate according to claim 8 , wherein the average value of the dimensions of the plurality of minutely deformed portions is 7 μm or more and 13.6 μm or less. The glass plate according to claim 1, which satisfies at least one relational expression of Y≦-1/6X+20 and Y≦-1/40X+8 when gloss is expressed as X (%) and haze is expressed as Y (%). The glass plate according to claim 1, wherein the coefficient of variation of the dimensions of the plurality of minutely deformed parts is 3% or more. The glass plate according to claim 1, which satisfies condition b that the number-based ratio of the micro-deformed portions B having the dimension exceeding 35.5 μm to the plurality of micro-deformed portions is less than 15%.

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